If you don't know the combination to a Master Lock[1]XResearch source combination lock, you have a few options. If your lock is attached to something, you can break the lock, call a locksmith or use a shim. However, these options could put a dent in your wallet. Sometimes, your cheapest option is to figure out the combination.
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There's a vulnerability in Master Lock branded padlocks that allows anyone to learn the combination in eight or fewer tries, a process that requires less than two minutes and a minimal amount of skill to carry out.
The exploit involves lifting up a locked shackle with one hand while turning the combination dial counterclockwise starting at the number 0 with the other. Before the dial reaches 11, there will be three points where the dial will resist being turned anymore. One of them will be ignored as it is exactly between two whole numbers on the dial. The remaining two locations represent locked positions. Next, an attacker again lifts the locked shackle, this time with less force, while turning the dial clockwise. At some point before a full revolution is completed, the dial will resist being turned. (An attacker can still turn through it but will physically feel the resistance.) This location represents the resistance location. The two locked positions and the one resistance position are then recorded on a Web page that streamlines the exploit.
Now that the attacker knows the first and last digits and knows the second digit is one of eight possible numbers, the hack is a simple matter of trying each possible combination until the correct one opens the lock. The following video provides a simple tutorial.
Kamkar told Ars his Master Lock exploit started with a well-known vulnerability that allows Master Lock combinations to be cracked in 100 or fewer tries. He then physically broke open a combination lock and noticed the resistance he observed was caused by two lock parts that touched in a way that revealed important clues about the combination. (He likened the Master Lock design to a side channel in cryptographic devices that can be exploited to obtain the secret key.) Kamkar then made a third observation that was instrumental to his Master Lock exploit: the first and third digit of the combination, when divided by four, always return the same remainder. By combining the insights from all three weaknesses he devised the attack laid out in the video.
It's by no means the only way to break the security of a popular padlock. It comes a few years after Master Lock engineers developed new padlocks that resisted a popular form of attacks using shims made from soft drink cans. Kamkar said he has tried his exploit on more than a dozen Master Lock combination locks, and so far it has worked on all of them. In the coming weeks, he plans to unveil more details, including an Arduino-based robot that streamlines the exploit.
While there are still many other ways to bypass a combination padlock, including the use of a shim, bolt cutters, locksmiths, or even a blowtorch, none are quite as elegant nor non-destructive as old school combination cracking.
In the case of a Master Lock, we simply clear the lock. This is accomplished by rotating the dial, at minimum, three times past the zero mark in the clockwise (right) direction. Additionally, be sure to stop the rotation at the zero mark as well.
First, you must again clear the lock by rotating the dial a minimum of three times in the clockwise direction. Then while continuing to rotate the dial clockwise, enter your first number.
Master Lock combination padlocks have been known to be vulnerable to an attack that reduces their 64,000 possible combinations down to 100. I've devised a new attack for cracking any Master combo lock that simplifies the process and reduces the amount of work down to only 8 combinations.
Same as others here, I have an older lock from maybe 5-6 years ago, serial on bottom reads 1211CF. Same trouble. The dial locks at 2-3, so I skip. The first locked position then is 5.5 and 6.5. Next, it locks between 9 and 9.8. Then the next locked position is 12.2 and 13.1. Next is 15.5 and 16.5. Kicker here is that I do know the combination on this lock, as it was never used and still has the sticker. Happy to work with you on this. Would like to help amend your code to make it universal if possible. Standing by.
Same problem Samy. The first two locations that it stops between two half numbers is 4.5/5.5 and 14.5/15.5. There's also a 7.8/8.8 but I tried 8 as my second locked position and none of the combos worked with either third digit. Resistant location is 2.
I'm trying this out and the numbers aren't matching w/ the combo that I know it works with. First stopping point is 2 & 2.9 which u explain isn't it. Second stop is 5.1 & 6, so thats not it ether. Third stop is 8.5 & 9.4, so I enter in 9 for First Digit. As I turn some more looking for the Second Digit, it's already passing 11. Next lock position is ether. 11.9 & 12.9 and 15.5 & 16.4. Suggestion?
Doesn't work for me. I know the combination and it gets the first and second numbers correct but not the third. The only options it gives for the third are 10 and 30 but the actual is 14. I know the first and second locked positions are correct and both are under 11 and the resistant location is either 4 or 4.5 but neither works
Worked for me. Not sure of the age of the lock. It took me a few times to get the feel for the various positions, but easier than cutting the lock or chain. First locked was a 1 and that threw me a bit. Developing a feel for the resistant position was tricky at first too. Hey it Worked!!
Well, I think I found the first 2 numbers I need to input, but I cannot find the resistant position! I've tried readjusting the amount of "lift" on the shackle, to no avail. I either feel no resistance at all, a sort of rattle resistance on Everything or locked. Advice?
I'd love to know the math too.. I had to combine this with the "in 100 tries or less" method. The 3rd number was wrong, but easily found manually, the 1st number seems to be generated based on the resistance number, and even though it worked it wasn't the right number (only 1 digit off so maybe human error or glitch in the matrix) but regardless, 1 digit discrepancy still works in most cases. And my 2nd number was also only 1 digit off.. But I could generate the right digit using the "100" algorithm.. This all makes me REALLY want this formula, because I feel like with a little tweaks you can have a definitive 3rd, 1st, and maybe narrow down the 2nd. It all makes me wanna grab a few more locks from the store to test some theories and equations
I found that the results of some tests depend on how I rotated the dial to set the starting point. Therefore I think that instructions starting with "Set the dial to" should indicate whether the position should be set by clockwise or ccw rotation of the dial.
Hi Samy, first of all, I got my lock open - so thanks! It did take me a few more than eight tries though so I thought I'd give some feedback in case you're interested or someone else finds it helpful.
This isn't working for me. My first lock up is between 1 and 2, next is between 4 and 5 then 8 and 9, then 10 and 11. I have none that go x.5 to y.5 between 0 and 11. I also can't find the resistance point. I get 3 or none.
I just tried a lock that I know the combination of and it doesn't work on that one either. My middle digit is 00 and none of the combinations give me 00 as an option. It also can't find the 3rd digit which is 33.
Took under 60 seconds for me to find the combo to an old lock I was going to throw away... Although I already knew ONE of the numbers, I wouldn't have believed it if I hadn't seen it with my own eyes.
I tried this several times with different master locks and it worked as outlined (I am used to using the 100 try method), but I came across a lock today that it would not work on. It's a master lock with a red dial and keyhole in the back. The numbers on the dial do not line up the same way they do on a standard master. I could not even do the 100 try method as I could not isolate the third digit. For this method however, I came close, but could not feel the Resistant Location. Thoughts anyone?
I really can't get the "resistance number." Maybe the lock I'm trying to get into (an older lock that I thought I had lost and had replaced) is too old and beat up. Maybe I'm simply not dextrous enough to understand how much pressure to apply to the latch. I simply don't get it. Can anyone help me with this part of it? My hands or my brain or a combination of the two simply don't get it.
You're absolutely full of shit, this doesn't work what so ever! I've tried so many combos that my hands hurt. My lock doesn't stop anywhere before 15 and there's no resistance besides at 12 which doesn't give me a third number. Thanks for wasting my fucking time.
Discovered a lock I haven't seen in years, of course, combo was long gone. I tried the technique, fully believing it was full of crap. The first and last numbers did NOT seem familiar....but I started trying middle numbers from the list, and lo and behold, the 4th number worked and the lock popped open.
I totally felt like I did the whole instructions thing wrong because nothing really felt for sure like it was truly resistant, but anyway...worked for me and I have my pretty purple master lock back without having to buy another!
I found an old lock that I used to use. I needed it for something and I forgot the combination. I didn't want to go out and but a new one so instead I used this website and I helped me out a bunch. I got my combo in 5 minutes super easy. Anyone wanting to know if it works , it works perfectly.
Samy, this worked for me like a charm on my standard-issue master padlock. Unfortunately, I have another padlock that has letters instead of numbers. Any thoughts on how to crack this one? Any help would be appreciated.
So trying this with a generic store brand (Ace hardware) and not succeeding...Seems the first locked position is actually around 0 (can jimmy between 0 and 1). On another site there's a thing about finding 12 locked position going counterclockwise..first off, I assume mine means the first is .5??? Second...I've tried multiple different approaches to this and cannot crack this brand. Is it different for generic? 2ff7e9595c
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